Reader Question: Should gasoline or kerosene be burned in a diesel engine?

diesel engine

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Scott, you are right, we had discussed the clear liquid shortening and I thought I had stayed away from it until I saw the cubies. Yesterday, I went back to my supplier and commented about the mixing of Clear Liquid Oil and Clear Liquid Shortening. Undoubtedly, the grill cook was not aware the oil had been mixed until I saw it on the cubies and so I've been told they have a new supplier and it will be only Clear Liquid Oil. I have asked them to keep the empty cubies for me, so I can use them for storage, etc. I will wait and see what happens.

The kero I had mentioned mixing with my biodiesel is considered highway kero with taxes paid on it at the pump. In N.C. all of our kero is dyed, as well as off road diesel. Our DOT will spot check big rigs, but so far I haven't heard of them checking small diesels. However, I never use dyed fuel in my pickup. Next door in S.C. all of the fuel is cheaper due to our state taxes being lower so the kero is actually cheaper than their diesel. Our kero is higher than our diesel and the diesel is 20 to 40 cents higher per gallon than our unleaded. Several years ago, I had an Olds with a GM diesel (converted gasoline to diesel) and the book allowed me to use 10 percent gasoline during the winter to keep the diesel from gelling. Do you think that would be wise to use gasoline in biodiesel during the winter?

My friend that I was splitting the oil with has backed out of using SVO I think mainly due to the mods he would have to do to his truck. Anyway, he left me with some literature he had pulled off the internet about using SVO and unleaded gasoline. I'm thinking that would be a great way to blow an engine or at least coke it pretty heavily in a short time. Looks like there is a little of everything on the net. Have a great day. Tom

Hey Tom,
As long as you can get highway kero, and it's cheaper, go ahead and run it with a mixture of at least B20 to keep the lubricity up. Kerosene is often used as a thinning (viscosity reducing) agent to help prevent diesel (middle distillate grade #2) and biodiesel fuel gelling in cold weather, but it does reduce the fuel's lubricity as well. Since biodiesel has a very high level of lubricity, the reduction from mixing with kerosene is minimal. With regular petro diesel, care must be taken to avoid over-thinning. To avoid this problem, most fuel distribution centers carry winter diesel (light distillate grade #1) for delivery to fueling stations in cold climates.

Diesel engines, however, are remarkably tolerant of fuel formulations and can run on just about any low volatility oil based fuel, but of course that doesn't mean they should or that it is even legal (tax wise) or beneficial to do so. While the engines themselves (pistons and valves) are more or less indifferent to fuel types, the emissions and injection controls on modern clean diesel engines would likely be damaged by using any fuel other than ULSD or B5.

For illustration purposes only, following is a (mostly complete) list of fuels that can be burned in a diesel engine:

  • Diesel #1
  • Diesel #2
  • Diesel #4
  • ULSD (Ultra Low Sulfur Diesel)
  • Biodiesel (from B5 to B100)
  • Kerosene
  • Home heating oil
  • Civil jet fuel (Jet A-1, Jet A, Jet B)
  • Military jet fuel(JP-4,JP-5,JP-8)
  • SVO (Straight Vegetable

And this is interesting—your fuel prices in the Carolinas are different than ours further north. In central PA as of 05-20-08:

No, the E85 price is not a typo. Ethanol based fuel has been about a buck a gallon cheaper for the last several years. I've been experimenting with varying percentages of E85 in my gasoline powered 5.7-liter 1994 Chevy Silverado. A story about my results as well as doing a full conversion to E85 is in the plans. Which brings me to your question about running a gasoline and SVO (straight vegetable oil) mixture in a diesel. I would steer clear for the very reasons you mentioned as well as others from horror stories I've heard. Diesels are compression ignition engines designed for dense, low volatility oil based fuels (diesel, biodiesel and kerosene). Gasoline style engines are spark ignited and require light and highly volatile fuels (gasoline, alcohol and E85). It doesn't take a stretch of the imagination to understand that an improperly-mixed amount of gasoline and vegetable oil (too much gasoline) could easily prematurely ignite (detonate) and destroy a diesel engine's pistons and/or valvetrain. Reciprocally, I've heard stories of mixtures with too much veggie oil gumming up and clogging filters, pumps and injectors.

In my opinion, there are only two safe methods to run vegetable oil in a diesel engine: Use properly manufactured biodiesel, or install a conversion kit that heats (thus reducing viscosity) the SVO before introduction to the fuel pump and injectors. As always, Tom, thanks for the great comments and questions.